Ethylene-α-olefin copolymers are molded into films, sheets, bottles, etc., by a variety of molding methods and are subjected to a variety of utilities such as food packaging materials.
Among the ethylene-α-olefin copolymers, a copolymer polymerized using a metallocene catalyst is known to be superior in a mechanical strength such as an impact strength and a tensile strength. For this reason, when such a copolymer is used, since its thickness can be reduced while a mechanical strength possessed by an article formed from an ethylene-α-olefin copolymer polymerized using a catalyst which is not the metallocene catalyst is maintained, weight saving and cost saving of articles can be expected. Therefore, utilization of the copolymer in a variety of utilities is studied. However, the ethylene-α-olefin copolymer polymerized using the previous metallocene catalyst is of a high extrusion load at extruding, and improvement has been requested.
To the contrary, nowadays, a novel metallocene catalyst has been studied, and an ethylene-α-olefin copolymer with improved molding processability, polymerized by the catalyst has been proposed. For example, Patent Literature 1 describes an ethylene-α-olefin copolymer polymerized using a metallocene copolymer comprising a transition metal compound having a ligand in which two groups having a cyclopentadiene-type anion framework are bound via a bridging group, a transition metal compound having two groups having a substituted cyclopentadiene-type anion framework which are not bound to each other, and a co-catalyst component for activation. In addition, Patent Literature 2 describes an ethylene-α-olefin copolymer polymerized using a metallocene catalyst comprising a co-catalyst component obtained by bringing silica, hexamethyldisilazane, diethylzinc, pentafluorophenol, and water into contact with each other, triisobutylaluminum, and racemic-ethylenebis(1-indenyl)zirconium diphenoxide. In addition, Patent Literature 3 describes an ethylene-α-olefin copolymer polymerized using a metallocene catalyst comprising a combination of a transition metal compound having a ligand in which two groups having a cyclopentadiene-type anion framework are bound via a bridging group, and a transition metal compound having a ligand in which a group having a cyclopentadiene-type anion framework and a group having a fluorenyl-type anion framework are bound via a bridging group, and a carrier obtained by treatment for carrying methylaluminoxane as a co-catalyst on a porous silica.    [Patent Literature 1] JP-A No. 2003-96125 gazette    [Patent Literature 2] JP-A No. 2004-149761 gazette    [Patent Literature 3] JP-A No. 2006-233206 gazette
However, although in the ethylene-α-olefin copolymers described in Patent Literatures 1 and 2, an extrusion load at molding processing is reduced as compared with the ethylene-α-olefin copolymers polymerized using the previous metallocene catalyst, further reduction in an extrusion load is requested, and the ethylene-α-olefin copolymer described in Patent Literature 3 was not sufficiently satisfactory in take-up property yet at molding.